Compact 8" for visual only

[anj026]

I'm mostly into refractors for visual only and own a few that are 6" aperture and less. I would love an 8" refractor but am a little daunted by the size and cost. If I did go that way it would most likely be an 8" f9 or f12 achromat lens in a home made tube and alt az mount to keep the cost in my affordable range.

This leads me to consider the alternatives within the same budget restriction.

Celestron C8, Vixen VC200L, Edge 8", Mewlon 210. I already own a Vixen GPD2 mount.

Alternatively I would be comfortable making my own newtonian with premium optics purchased from the US. In order to keep things compact I was thinking of an 8" f4.5 with paracorr and approx 27% obstruction (less than the cassegrains).

I am interested to hear from anyone that has used a Vixen VC200L and compared it directly with a C8 for visual. I think it is more appealing due to the lack of corrector plate and because it has a fixed primary and fixed focal length. Is it as good visually? I would expect the Mewlon to be the best of the bunch but it is almost twice the price of the Vixen. The Edge 8" could be nice but by the time I added a Vixen rail the cost for the ota would be nearly $2400. I think the VC200L ota is about $1900.

What do you think?

Andy

[gb_astro]

Andy I'm sure we would all rather watch you build that 8" f12 refractor monster.

gb.

[anj026]

Thanks gb, my heart says go for it but my head says hang on a minute!

I started a thread on CN and the answers I got regarding the Vixen have basically ruled it out for me. Sounds like a great scope but probably no better than the refractors I already have for visual purposes.

I would really like to try a cassegrain but it seems a good 8" one for visual will be more than $3500. On the other hand a Royce 8" f4.5 conical mirror, Starlight SIPS focuser and other bits and bobs in a home made tube would be under $2500. Not as compact as a cassegrain but still not too large for the GPD2 and should beat the pants off an 8" SCT for visual.

Andy

[astroboy]

Hi Andy
I wouldn't bother with a Coma corrector for a 8" F4.5 , I have a 8" F4 travel scope and gives great images with Naglers ( 13mm and 7mm type 6 ).
So unless you can see your self doing imaging save the money and put it towards some Naglers if you don't already have a few.
Strangely the 13mm Ethos isn't so good and the 24.5 Meade SWAs are bad off axis.
When I had an 18" F4.5 the only time I liked to use a CC was with a 27mm Panoptic , with the 24" F3.6 the Parracorr 2 is needed .

Zane

[netwolf]

+1 for a C8 or Meade 8" SCT, I love these scopes. You can go visually down to F6.3 and up to F10 and beyond. And they are just so compact. The LX90 scope I had previously was my most utilised scope.

I imported my C8 Fastar (late 80'e early 90's model) from the US. And these days I have seen a few come up on Amart for as little as 300$. If you can convince someone to ship it over to you then its a steal. The shipping costs go up if you include mounts like a Nextar SE setup, but still a bargain compared to local pricing. And the Nexstar SE mount is a nice portable moutn no polar alignment just plonk and go. For visual this is a great setup. Also check Optcorp they have used ones on there that they will ship over. You can ask for a cheaper surface shipping option also.

[Waxing_Gibbous (Peter)]

Mewlons I find are touchy about collimation and fiddly with it.
Its very hard to beat the 8" offerings from Meade and Celestron in their price range.
However, I too would rather see someone build a Royce mirrored, CF tubed newt with auto-collimation and water cooling. Get busy!

[stringscope (Ian)]

G'Day Andy,

Given your exceptional telescope making skills, I reckon the Newtonian option might be the best way to go for the following reasons:

1. Potentially lowest cost

2. Wood tube

• has potential to be quite light
• dimensions/baffling/light shield can be customised to suit your application
• is thermally stable
• Looks great

3. F4.5 Newtonian with coma corrector/flattener when correctly built and set up

• provides bright pleasing visual images
• with practice and correct tools is easy to collimate

A couple of other thoughts:

You could reduce the cost a little by going to a Moonlite focuser and standard TV Paracor compared to the FT with integral PC.

With a focal length of 900mm I suspect most of your observing might be with shorter length eyepieces.

Cheers,

[anj026]

Zane, I have assumed I would need a paracorr but I guess it would be prudent to try the scope first and see how it went without one. One of the attractions of the SIPS focuser for me is that it does away with having to adjust the paracorr when changing eyepieces, I like the sound of that but I have no experience with paracorrs or fast newtonians (I did have a 6" f5 travel newtonian a long time ago, you may recall seeing it when we met at the 1998 Astrofest at Coonabarabran). I do have some Naglers.

Fahim, I can see the attraction of an 8" SCT though I have no experience with them. I don't like what I here about them with regards to dew issues and cool down problems. Obviously they are popular and there are ways of overcoming these problems. It is tempting to get one one and find out for myself whether I can live with it.

Peter, call me old fashioned but wood and air cooling are my prefered methods.

Ian, thanks for the compliment and I agree a good newtonian has the potential to give the best performance for the dollar.

Andy